Facts: 1925 cinder block basement wall (supports 1-1/2 stories) has two vertical cracks (pretty much entire height of wall). Have monitored split for 2 years (with glass crack monitoring devices) and no movement. Was in this condition when we bought the house (yes, I know how dumb it is now). Inspected footer…no damage to footer. The loads are well supported throughout the house and overload was likely not the cause of the cracks (clear evidence of one being induced by water intrusion at poorly installed window edges another at an ill-advised and poorly executed wall breach for utilities). Note: I had a colleague engineer verify my findings on the structural condition (I am also a professional civil engineer).
Questions: I would like your opinions on the best way to repair an old cinder block wall with a vertical crack (ie, a crack that alternates along its length between mortar and the center of the block). The crack is 1/2″ at most and as I stated above is not expanding. Would Epoxy injection be suitable or feasible? Would the voids of the block make epoxy injection pretty useless? Would the relatively new liquid/plastic concrete injected in be an option? How about filling the voids with low-expansion spray foam, cutting this back and then pointing the cracks or injecting epoxy?
Much thanks,
Tim
Replies
Epoxy would be my choice, but it really won't do much for you since it is stabilized already, unless you are also willing to dig down outside and do the same to both sides of the wall, presuming that you have the same crack through it.
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Tim there is a new process being touted for cracked foundation walls:
http://www.stablwall.com/
The couple of installations I have seen look like fiberglass mats applied to the wall, but is supposedly space age miracle stuff .
I have my doubts as to how good it is in preventing further movement (seems to me the issue is the mat to wall adhesion - not the strength of the mat) but you might want to take a look.
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Epoxy injection would probably not be the way to go for cinder block. Too many voids. Epoxy injection is suitable for smaller, hairline cracks. Not to mention, most epoxy injection contractors charge by the amount of epoxy injected, and with large voids, this will get really expensive fast. Also, epoxies won't set up properly if the void is too large - I think it's anything over 1/4-inch. Epoxies generate a lot of heat while they set up - too much if you have too much epoxy.
Thanks for the replies all.
So, to summarize, epoxy does not make sense for wide cracks and is out of the question for large voids (such as the interiors of cinder block). This is helpful to know. How about if I used a combination of filling the voids with expanding foam (slow expansion), then trimmed the foam back to reveal the crack. I would then have the epoxy injection along just the crack area. Or would it just make more sense to properly point this crack with appropriate the mortar after filling the voids with foam?
As to the question of digging down outside and fixing the cracks inside and out: this is a "walk-in" basement on the side with the cracks and digging is not an issue. I plan to to interior and exterior fixes and do them proper.
Now about the fiberglass overlay product...I'll take a look. If anyone has experience with this, it would be helpful.
Thanks,
Tim
myself, I would hammer a hole in the top block and try to fill with wet grout
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brownbagg,
Sorry to be a dunce, but do you mean fill the whole thing with wet grout until it comes out of the seams? I don't mean to imply that I think it is improper, just curious what you mean exactly...
Tim
I think that's what he means. In block construction it's common to fill certain cores, say, around a vertical rebar, or on both sides of a door opening with a fairly loose mix. The process is called "grouting". You'd have to make up a quick form, say a strip of 3/4" plywood, and brace it against the wall to cover the crack so the grout won't ooze out.
The grout should be loose enough to drop to the bottom, but not so much water that there's no strength left when the water cures and evaporates. You could use pea stone in the mix.
After the grouting is done, make a stiff mix and patch the hole.
yes, I would just use plain grout between each end of block, if it was in the center of block I use some peagravel. My whole house is filled every cell to ridge line, only eight yard. But one seam one crack couple bag cement maybe a wheel barrow load or less.
The best employee you can have but you wouldn't want him as a neighbor " He the shifty type"
Thanks all.
I understand now.
I guess the only problem that I have now is that these are the old-fashioned faux stone blocks (where the exterior side is textured to look like wavy stones). Although sealing the interior with a form will be simple, doing so on the outside would be a little tricky. My only thought on how to do so would be to apply duct tape over the crack.
Cheers,
Tim